The organization of cells in the cat dorsal horn will be examined with regard to cutaneous input. Intracellular recording, in conjunction with dye-injection, will be used to investigate correlations between physiological properties and cell geometry. Computer analysis of discharge timing will be used to analyze synaptic relations between afferent fibers and dorsal horn cells, as well as between pairs of dorsal horn cells, using extracellular recording. Source-sink mapping will be used to delineated the spatiotemporal patterns elicited by single action potentials in single, identified cutaneous afferents.